1. Field of the Invention
This invention relates to a system which is environmentally friendly while processing self-developing photographic film, in that, it uses materials which are largely reusable and recyclable. The system of this invention collects the trash and other residue from the developing process and deposits it in a container for transportation to a recycling center.
2. Description of the Prior Art
Self-developing, peel-apart film units are well known in the field of instant photography. Each film unit comprises a negative or photosensitive film sheet for forming a negative image of a subject, an image receiving film sheet for forming a positive subject image thereof and a rupturable pod of processing liquid. A positive image is formed on the positive sheet by means of a well known diffusion transfer process after the pod containing the processing liquid is ruptured and its contents spread between the positive and negative film sheets.
Film units of the aforementioned type are typically exposed in portable, multiple-exposure, instant-type photographic cameras or processed in large format film processing equipment. When employed in a camera as many as ten film units are provided in a single lightweight film pack, in a stacked relation, with the positive sheet on one side and the negative sheet on the other side of a pressure plate located within the film pack. Pull tabs are attached to one or both of the leading ends of the positive and negative sheets. After exposing an outer-most negative sheet at a film plane of the camera, a first tab attached to the negative sheet is withdrawn from the camera forcing the exposed negative to be turned 180.degree. about the pressure plate and into superposition with the positive sheet. This movement causes a second tab attached to the forward ends of the positive and negative sheets to enter the bite of a pair of pressure applying spread rollers. A combination of the angle at which the first tab is attached and the force applied by a camera operator causes the first tab to detach from the negative sheet at this time.
After the first tab is so detached, the operator pulls the second tab so as to advance the positive and negative sheets between the pair of spread rollers in a superposed relation. At the beginning of the advancement of the positive and negative sheets the spread rollers apply pressure to a pod containing a processing liquid located at the leading ends thereof, thereby rupturing same, and spreading its contents between the superposed sheets in a thin uniform layer as the sheets are advanced therebetween. A positive image is formed on the positive sheet outside of the camera by a well known diffusion transfer process. After a required interval of time the positive image is manually peeled away from its associated negative and the negative, along with the second tab attached thereto, are discarded. A more detailed description of this particular type of peel-apart film may be found at pages 185-187 of a book entitled, "Camera Technology" by Norman Goldberg published in 1992 by the Academic Press.
The above-described peel-apart film format has several disadvantages, especially if considered for use in certain photographic apparatus. One disadvantage is film cost. In addition to the multiple tabs and the relatively large amounts of leader material required for each film unit, which necessarily increases material costs, economies of scale are limited by the fact that both a positive and a negative sheet must be included within a single film cassette. Including significantly larger numbers of film units within a single cassette in order to take advantage of such economies would substantially increase cassette size and thereby make such a cassette unwieldy for use by a camera operator. Another disadvantage is that this type of film format is not susceptible of inclusion in highly automated film processing equipment. processing a film unit by pulling certain tabs at various times in the film processing cycle is clearly a processing technique that is inherently manual.
Another disadvantage of this system is the environmentally unfriendly result of disposal of trash from the film developing process where the negative film sheet, empty pod and spent developer liquid are stripped from the positive and deposited in conventional trash containers on the street.